Had a strange and sudden fuel delivery issue on my 1950 Flathead 6 this weekend. Was running along fine, then started to stutter in 4th gear with heavy throttle input, like a complete fuel cut. Backing off cancelled it, and it ran fine. Then it did it in 3rd and 4th gear, both with heavier throttle inputs, but it was definitely getting worse.

Looking it over: Truck as fuel, glass bowl of fuel pump is full, but definitely picked up a slight odor of fuel under the hood and noticed moisture on the outside of the fuel pump main body where it screws together over the diaphragm. Looks like it's either losing fuel under higher pressures or is pulling air (or both). I've done some research on here, and it doesn't seem to be a common area for failure (not a cracked housing and diaphragm still seems intact enough to function under light loads).

I'd rather just do a rebuild, and am wondering what luck people have had with the rebuild kits. I've done it on old Volvo fuel pumps, and it never quite lasts as long as you would hope (probably due to inferior kits).

And can I do a rebuild with it on the truck if I am just changing the diaphragm out? I'll probably run all new fuel lines while I'm at it, as these look to be original.

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These pumps are very simple and a snap to rebuild, but I'd recommend pulling the pump off the engine. That compression fitting does look to me like it's loose. If it were me I wouldn't replace any fuel lines that have been working fine.

 

I was thinking the "if it ain't broke, don't fix it" approach to fuel lines, so thanks for edging me in that direction.

I'll check the compression fitting later tonight to see if it's a bit loose. It's the same basic design as my old Volvo pump (just a bit bigger), so I'm not averse to the rebuild. Is there a kit you recommend that's better than the others?

 

You might check with VANPELT SALES LLC - your ford flathead source since 2006
I didn't see a fuel pump rebuild kit on his website doing a quick look, but he may have a line on a quality kit for you. I think it would definitely be worth a phone call.

 

 

auto? Charlie?

 

I appreciate all the info, fellas.

The compression fitting was snug, so that's not the issue. Definitely leaning towards the diaphragm possible being ripped or at least not sealing correctly.

I did some searching last night and it seems tough to find rebuild kits for the 6 cyl fuel pump. Is it that different than the V8 (aside from the actuating rod)?

If I can't find a kit at Then & Now, I may take it off and ship it to Cowboy John down in FL, the guy who rebuilt my water pump. He did outstanding work on that, and does fuel pumps, too.

 

Just because the fitting is tight, snug, does not mean it is not leaking. That area appears to show signs of gasoline having washed the dirt from it at some recent time. Just don't let anyone talk you out of that pump which is rebuildable. Many are not. BTW, rebuilding one of these pumps is about as easy a job as you can perform on one of these old vehicles.

 

Maybe the compression inside the fitting isn't what it used to be, but I'd have to rectify that with a new fuel line from pump to carb. But I'll try it by cleaning & re-seating the fitting first.

Because this engine is all original, I'd rather keep the original pump via a rebuild. That's the option I'm going with. It just depends on who does the rebuild. It will be me if I can locate the kit (done it before on old Volvo fuel pumps) or someone else if the kit can't be located (Cowboy John stocks the parts to rebuild these, as I've used him for the 6 cyl water pump rebuild). I'm not averse to doing the work myself if I can find the parts, and I'm not about to throw away a good old part.

My question about the V8 pumps has to do with the rebuild kits. There seem to be more of those available, and they appear to be the same basic pump design with the exception of the actuating lever. I wasn't thinking about putting a new V8 pump on this, just using that kit if I could. Thoughts?

 

If you have the right type of tubing cutter that will just cut off the ferrule (olive, in British) you have some wiggle room in the fuel line to install a new ferrule and make it up proper.

 

Bumping this up...

Finally had a chance to go tinker with it again. Took it out for a spin (first time since I posted this) and it did it again. Much more pronounced stutter/fuel cutoff. Really smelled gas under the hood when I shut it off this time.

Fuel pump exterior was dry, glass bowl is full.

But carb and intake were quite damp...with fuel under the float bowl of the carb. I took off the air filter, and there was a lot of fuel in the carb. But it was the fuel coming out from the accelerator pump linkage that had me most concerned. When I pumped the throttle (truck was not running), fuel ran out of that linkage, so I think I found my problem. I'm assuming a rubber o-ring or seal failed in that area, as a leaky accelerator pump or failed power valve shouldn't cause fuel to leak out of that area. Correct me if I'm wrong. I'm more familiar with later model Holleys 4 bbls and SU carbs than these old single barrel Holleys. Pics are below.

Should I try a rebuild on this (probably send it out due to time constraints) or is this a terminal sign? The leak is coming seems to be coming from the nut that holds the linkage to the carb body. I tried tightening that nut, but it didn't affect anything.

And I'm assuming this would be related to the fuel cutoff/stutter under load.

 

Cowboy John goes to Carlisle and Hershey next month, if you go he may be able to fix things there, give him a call and see

Ed

near Philadelphia

 

I had him rebuild my water pump, so he's definitely the guy I'd go to for this. I won't be able to make it to Carlisle due to work, but I can shoot him an email. He'll likely be backed up in Sept. due to those shows, so I may have to wait a bit for a rebuild if send it to him. He probably has a rebuild already, just needs mine as a core (that was one of his offers with the water pump, too).

 

Got the rebuilt carb back from Cowboy John Plaskan. I wound up sending him an 847 I got off of ebay instead of my original leaky one, as I needed to be able to move the truck in and out of the garage due to ongoing projects. $225 + $14 for return shipping and this is what you get!! He rebuilds it for use with ethanol fuel, if needed.

Truly plug & play. Took 10 minutes to swap it out and it fired right up. I just had to tinker with the idle screw a bit.

I am now getting a wicked misfire, and it sounds like the rotor is contacting the inside of the dizzy cap. I checked underneath the cap (which was VERY loose) and there are grooves in the contacts. I'll get a new cap and rotor and see if that helps. Didn't seem like there was much play in the shaft, so hopefully it's just a poorly-fitting cap.

I will also be sending the fuel pump down to Cowboy John over the winter, as that is still seeping a bit and should also be rebuilt for ethanol fuel as well. But I'll do that when I don't need to move the truck for a while. His turnaround time is approximately 3 weeks, btw.